Great insights into the functioning of the oculomotor system have recently been obtained through the recording of neuronal firing patterns during eye movements in alert monkeys. Many neurons whose activity is tightly locked to eye movements are found in the pontine reticular formation (PRF). These studies, however, tell nothing about where the neurons go and from where they receive inputs, that is, the wiring diagram. Within the last year or two electrophysiology has provided the first convincing evidence that several groups of PRF, parabducens, and MLF neurons send axons up the medial longitudinal fasciculus (MLF) to presumably synapse with oculomotor neurons. These PRF neurons were detected through antidromic activation from the MLF or the oculomotor nucleus. Although anatomists have described afferents to the PRF from important eye-movement structures such as the vestibular nuclei, cerebellum, and superior-colliculus, only through the intracellular recording of synaptic inputs from such structures can synaptic connections be demonstrated to PRF-MLF neurons. Present anatomical techniques are impotent for this task. The second experimental objective is to study the electrophysiology of the cells. Peculiar properties of cell membranes or synapses might intrinsically perform certain of the eye-movement signal-generating functions. The experimental procedure will follow the one already successfully used. After removal of the cerebellum, a stimulating electrode will be placed into the MLF just caudal to the trochlear nucleus for antidromic identification of PRF-MLF neurons. One or more stimulating electrodes will be placed into the vestibular nuclei, the superior colliculus, or the cerebellum to produce EPSPs or IPSPs in PRF-MLF neurons.